Apache Flink episode 1: A comprehensive introduction

First published on April 26, 2023

Last updated at June 1, 2023


9 minute read

Guest post by Shashank MishraData Engineer @ Expedia



Apache Flink

is a powerful open-source stream processing framework for big data, offering real-time and batch processing capabilities. With its flexibility and scalability, Flink is ideal for use cases like fraud detection, log analysis, IoT (Internet of Things), anomaly detection, and machine learning, making it a go-to solution for organizations needing real-time analytics and insights.


  • Introduction to Apache Flink

  • The evolution of Flink and its place in the big data ecosystem

  • Key features and benefits of using Flink

  • Flink’s architecture and components

  • Real-world use cases and success stories

  • Conclusion

Introduction to Apache Flink

Apache Flink is an open-source, distributed stream processing framework designed to handle large-scale, high-throughput, and low-latency data processing tasks. It can process both 


(real-time) and 


(historical) data, enabling organizations to derive insights from massive data sets in near real-time. Flink is widely used for various big data applications, such as 



machine learning

, and data analytics. At its core, Flink provides a robust data processing engine that supports event-time processing and windowing, allowing for accurate and timely analysis of time-based data.




The evolution of Flink and its place in the big data ecosystem

Initially developed as the Stratosphere research project at the 

Technical University of Berlin

, Apache Flink was accepted as an 

Apache Incubator project

in 2014 and became a top-level Apache project in 2015. Flink has since evolved rapidly, addressing the growing need for 


data processing and emerging as an integral part of the big data ecosystem. It's an integral part of the big data ecosystem, positioning itself alongside other popular data processing frameworks such as 

Apache Hadoop

Apache Spark

, and 

Apache Kafka

. While 


focuses on 

batch processing

with added support for streaming, 


is primarily a

stream processing

framework with added support for batch processing.




Key features and benefits of using Flink

  • True stream processing:

    Apache Flink's core strength lies in its ability to handle real-time data processing with minimal latency. Its true stream processing capabilities enable organizations to derive instant insights and make data-driven decisions, empowering them to stay ahead in today's fast-paced, competitive landscape.

  • Fault tolerance:

    Flink offers robust fault tolerance mechanisms, including checkpointing and state management. These features provide strong guarantees for exactly-once processing, ensuring data integrity even in the event of failures. This level of reliability is critical for applications where data consistency and accuracy are paramount.

  • Scalability:

    Flink's architecture is designed to scale seamlessly, handling massive data volumes with ease. Capable of processing millions of events per second while maintaining low latency, Flink is an ideal choice for organizations looking to manage ever-growing data streams without sacrificing performance.

  • Flexible APIs:

    Flink provides a diverse set of APIs tailored to different use cases and programming styles, such as the DataStream API for streaming data, DataSet API for batch processing, Table API & SQL for high-level, declarative data processing, and Stateful Functions for building complex, stateful applications. This flexibility allows developers to choose the most suitable API for their specific requirements, fostering innovation and creativity.

  • Extensible and modular:

    One of Flink's most attractive features is its extensibility and modularity. The framework can be easily customized and extended to support a wide range of data sources, sinks, and custom state backends. This adaptability enables organizations to seamlessly integrate Flink into their existing data infrastructure, unlocking new possibilities for data processing and analytics.

By offering a potent combination of true stream processing, fault tolerance, scalability, flexible APIs, and extensibility, Apache Flink has emerged as a compelling choice for organizations seeking to harness the power of big data and unlock valuable insights in real-time.




Flink’s architecture and components

Apache Flink's architecture

is built upon a set of powerful components that cater to diverse data processing requirements, making it an adaptable and flexible solution for various use cases.

  • DataStream API:


    DataStream API

    is Flink's primary API for processing unbounded streams of data in real-time. It supports time-based windowing, event-time processing, and rich state management features, allowing developers to build complex stream processing applications with high accuracy and low latency. The API also includes support for advanced features such as watermarks, timers, and stateful operators, enabling users to tackle challenging real-time analytics tasks with ease.

  • Table API & SQL

    : The 

    Table API

    is a high-level, declarative API for both batch and streaming data processing. It offers SQL-like syntax, making it easy for users familiar with SQL to work with Flink. The SQL API, a subset of the Table API, offers standard ANSI SQL support, enabling seamless integration with existing tools and systems. With support for advanced features like time-based operations, user-defined functions, and windowing, the Table API & SQL simplify the development of complex data processing applications, reducing the learning curve for new users.

  • Stateful Functions:


    Stateful Functions

    is an event-driven, serverless framework built on top of Flink. It provides a way to build complex, stateful applications using a functional programming model. By combining the scalability and fault tolerance of Flink with the simplicity of stateless functions, Stateful Functions allows developers to create highly available, distributed applications that can process large volumes of events while maintaining consistent state. This framework is particularly well-suited for microservices architectures, IoT applications, and other use cases where state management and event-driven processing are essential.

Apache Flink empowers developers and organizations to address a wide range of data processing challenges, from real-time analytics to large-scale batch processing, with ease and efficiency. Flink's modular and extensible architecture ensures that it remains a versatile and valuable tool in the ever-evolving big data landscape.




Real-world use cases and success stories

Apache Flink's versatility and low-latency processing capabilities make it ideal for various use cases across industries:

  • Financial fraud detection:

    Banks and financial institutions, like 


    , use Flink to process massive transaction volumes in real-time, detecting and preventing fraud effectively.

  • Log and event analysis:

    Companies such as 


    utilize Flink to process and analyze billions of events daily, enhancing operational efficiency and user experience.

  • IoT data processing: 

    Flink's low-latency processing is ideal for ingesting and analyzing IoT data. 


    uses Flink for predictive maintenance and real-time monitoring in connected industry solutions.

  • Anomaly detection:

    Flink identifies unusual patterns in time-series data, useful in network monitoring and cybersecurity. 


    uses Flink for real-time anomaly detection and network monitoring.

  • Machine Learning:

    Flink's integration with popular machine learning libraries allows users to build large-scale, real-time machine learning applications. 


    uses Flink for machine learning pipelines to improve customer experience and detect fraud more efficiently.

These success stories showcase Flink's potential in addressing complex, large-scale data processing challenges across various industries, powering data-driven insights and real-time analytics.


In conclusion, Apache Flink has emerged as a powerful and flexible stream processing framework in the big data ecosystem. Its ability to handle both streaming and batch data, along with its rich APIs and fault-tolerant architecture, make it a popular choice for various data processing applications. The numerous real-world use cases and success stories demonstrate Flink's potential in addressing complex, large-scale data processing challenges. As the demand for real-time analytics and insights continues to grow, Apache Flink is well-positioned to help organizations make the most of their data.

In episode 2 of Apache Flink series, we'll compare Apache Flink with Apache Spark and find out their differences.